1. Field of the Invention
The present invention relates to a transmission used in a vehicle. More particularly, the present invention relates to a synchronizing device for a manual transmission that performs synchronizing action smoothly by eliminating an oil film from a blocker ring and a cone surface of a clutch gear during only key load is exerted when synchronizing.
2. Description of Related Art
Generally, a transmission is a part of a power delivery device. The transmission is disposed between a clutch and a drive shaft so as to increase or decrease engine torque according to a driving condition of a vehicle. In addition, the transmission has a reverse device for reversing the vehicle.
A synchronizing device of a manual transmission prevents shift shock through a smooth connection of gears by engaging a driving gear with a driven gear after rotation speeds of the driving and drive gears are synchronized when the driving gear is engaged with the driven gear.
FIG. 1 is a partial cross-sectional view of a conventional synchronizing device.
Referring to FIG. 1, a conventional synchronizing device includes a clutch hub 100, a sleeve 102, a blocking key 104, a blocker ring 106, and a clutch gear 108.
The clutch hub 100 is splined to a rotation shaft (not shown), and a plurality of recesses is formed at an exterior circumference thereof along a circumferential direction with even distances.
The sleeve 102 is splined to the exterior circumference of the clutch hub 100 and is movable in an axial direction. A sliding recess 110 is formed at an exterior circumference of the sleeve 102, and the sleeve 102 can move to the left or the right in the drawing by a shift fork (not shown) inserted in the sliding recess 110.
Each blocking key 104 is disposed in the plurality of recesses formed at the external circumference of the clutch hub 100 along the circumferential direction thereof with the even distances. A spring 112 is interposed between the blocking key 104 and the clutch hub 100, and the blocking key 104 is inserted in a locking groove 114 formed at an interior circumference of the sleeve 102 by elastic force of the spring 112.
The blocker ring 106 is typically called a synchronizer ring. The blocker ring 106 is disposed at both sides of the clutch hub 100 so as to protect the blocking key 104 and is adapted to be pushed by the sleeve 102 when the sleeve 102 moves in the axial direction so as to be frictionally synchronized with a cone surface 116 of the clutch gear 108.
The clutch gear 108 is integrally formed with a speed gear (not shown).
According to the synchronizing device, if the sleeve 102 is moved to the left or to the right in the drawing for shifting, the blocking key 104 as well as the sleeve 102 moves and pushes the blocker ring 106 to the clutch gear 108.
Then, an interior circumference of the blocker ring 106 is rubbed with the cone surface 116 of the clutch gear 108 such that rotation speeds of the clutch gear 108 and the blocker ring 106 are synchronized. If the sleeve 102 moves further at this state, the sleeve 102 and the clutch gear 108 are engaged with each other and power delivery is achieved.
FIG. 2 and FIG. 3 are a front view and a top plan view of a blocker ring used in a conventional synchronizing device.
Referring to FIG. 2 and FIG. 3, three servo load exerted portions 118 and three key load exerted portions 120 are formed at an exterior circumference of a conventional blocker ring 106 alternately.
The servo load exerted portion 118 represents a portion of the blocker ring 106 where supporting protrusions 122 and 124 for receiving the blocking key 104 are formed, and the key load exerted portion 120 represents a portion of the blocker ring 106 where a side of the blocking key 104 is contacted.
When the blocker rings 106 are disposed at the both sides of the clutch hub 100, the servo load exerted portion 118 of the blocker ring 106 disposed at one side and the key load exerted portion (not shown in the drawing) of the blocker ring (not shown in the drawing) disposed at the other side are disposed collinearly and the blocking key 104 is coupled therebetween.
Therefore, six blocking keys 104 disposed between the servo load exerted portion 118 and the key load exerted portion 120 pushes the blocker ring 106 disposed at the selected side, and thereby operates as the synchronizing device.
According to the conventional blocker ring 106, the key contacting surfaces 126 and 128 of the servo load exerted portion 118 and the key load exerted portion 120 are disposed on the same plane.
FIG. 4 is a schematic diagram of a conventional synchronizing device with a sleeve not being assembled for showing positions of a key and a blocker ring at a neutral state, and FIG. 5 is a schematic diagram of a conventional synchronizing device with a sleeve being assembled for showing positions of a key and a blocker ring at a start region of synchronization.
Referring to FIG. 4, a clearance C between the key contacting surface 126 of the servo load exerted portion 118 and the blocking key 104 is the same as that C between the key contacting surface 128 of the key load exerted portion 120 and the blocking key 104.
If the sleeve (not shown in the drawing) pushes the blocking key 104 in order to start synchronization, the blocking key 104 are simultaneously contacted to the key contacting surfaces 126 and 128 of the servo load exerted portion 118 and the key load exerted portion 120 as shown in FIG. 5, and synchronizing force is delivered.
Therefore, a time for eliminating an oil film remaining between the cone surface 116 of the clutch gear 108 and the blocker ring 106 may be insufficient and necessary frictional force may not be generated.
Even though the necessary frictional force is not secured as described above, serious problems may not occur in a normal shifting. However, synchronization is hard to be performed and smooth shifting may not be achieved in abrupt shifting.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.